% -*- mode: latex; fill-column: 80; -*-
\documentclass[tikz,convert={outext=.png,size=400}]{standalone}
\usetikzlibrary{decorations,positioning}
\begin{document}
\begin{tikzpicture}
\node[draw,circle] (M) at (0,0) {$\prod$};
\node[draw,above left=1cm and 1cm of M] (C1) {$C_1$};
\node[draw,below left=1cm and 1cm of M] (C2) {$C_2$};
\node[draw,right=1cm of M] (C3) {$C_3$};
\node[above=0.3cm of C1] (I1) {\includegraphics[width=1.5cm]{tri.pdf}};
\node[above=0.3cm of C2] (I2) {\includegraphics[width=1.5cm]{rec.pdf}};
\node[above=0.3cm of C3] (I3) {\includegraphics[width=1.5cm]{cos.pdf}};
\node[below=0.3cm of C1] (N1) {\includegraphics[width=1.5cm]{no1.pdf}};
\node[below=0.3cm of C2] (N2) {\includegraphics[width=1.5cm]{no2.pdf}};
\node[below=0.3cm of C3] (N3) {\includegraphics[width=1.5cm]{no3.pdf}};

\draw[->] (C1) -| (M);
\draw[->] (C2) -| (M);
\draw[->] (M) -- (C3);
\draw[->] (I1) -- (C1);
\draw[->] (I2) -- (C2);
\draw[->] (I3) -- (C3);
\draw[->,decorate] (N1) -- (C1);
\draw[->,decorate] (N2) -- (C2);
\draw[->,decorate] (N3) -- (C3);
\end{tikzpicture}
\end{document}

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